Conventional electrical power outlets or outlet strips generally have fixed locations. In order to connect to a device or an appliance that is located far away, an extension cord or extension socket is normally used. However, when the number of devices or appliances increases, the additional cords and/or extension sockets not only make a room look untidy but also cause safety issues. Alternatively, more sockets may be installed on the walls to meet the increased number of appliances and/or devices. However, more sockets require more complexed wiring inside the walls. Also, it is difficult to predict how many outlets are needed and where to install them in a house because different people may have different demand.